Color display calibration is described in U.S. Pat. Nos. 6,043,909, 6,157,735, 6,459,425 and 6,750,992, in which sensor configurations are presented for different display types. One such type of arrangement is suited to a projection display as described, for example, at column 16, lines 31-35, of U.S. Pat. No. 6,043,909. Such sensors were located near the source of projected light and were as close as possible to the line of sight. However, many contemporary displays used in large screen applications, such as home theatre or commercial projectors, may benefit from color calibration to assure color accuracy, and further may represent rendering devices useful for virtual proofing described in the above U.S. patents.
Further, often color display are not uniform over their field of view, and thus areas of such display may be appear brighter than others, and may appear to have different color balance amongst different color channels at different points. Thus, it would also be useful to detect non-uniformities in color displays and correct for such non-uniformity, thereby providing consistency in displayed color. Furthermore, it would be useful if such detection and correction of non-uniformity may be extended to other rendering devices, such as printers and presses.